The mammalian brain depends on glucose as its main source of energy. In the adult brain, neurons have the highest energy demand, requiring continuous delivery of glucose from blood. In humans, the brain accounts for ~2% of the body weight, but it consumes ~20% of glucose-derived energy making it the main consumer of glucose (~5.6 mg glucose per 100 g human brain tissue per minute . Glucose metabolism provides the fuel for physiological brain function through the generation of ATP, the foundation for neuronal and non-neuronal cellular maintenance, as well as the generation of neurotransmitters. Therefore, tight regulation of glucose metabolism is critical for brain physiology.
Considering importance of glucose for brain cells, rate of glucose consumption is monitored by PET scan in coma patient’s to differentiate between patient’s in total coma and those with hidden sign of awareness.
Recently researcher’s from University of Copenhagen and Yale university used technique FDG-PET to monitor sugar uptake in brain of coma patient’s to see energy signatures, they analyzed glucose uptake and neuron metabolism in patient’s with partial or full unconsciousness and then compared those results to whether or not a patient had woken up in a year’s time. They found that those who showed less than 42 percent of normal brain activity didn’t regain consciousness after a year, while those who had activity above that woke up within a year. Overall, the test was able to accurately predict 94 percent of patients who would wake up from a vegetative state.
it’s a very promising step towards a test that might offer families of patients with brain injuries some idea of what to expect in the next year, for better or worse.